1. Field of the Invention
The present invention relates to electric part in the form of windings, particularly suitable to be used as a compact transformer.
2. Background Art
Various electric parts in the form of windings are well known, including such part having a plurality of choke coils, the unitary part consisting of multiple transformers and the unitary part comprising choke coil/transformer combination.
Among these parts, the transformer usually comprises a bobbin having a cylindrical coil supporting portion around which a low voltage coil and a high voltage coil are wound and a core having a portion inserted into the inner cavity of said coil supporting portion and the remaining portion axially extending around the coils.
When various coils are wound around a single bobbin, the respective coils may be wound one upon the other directly or lap-wound with interposition of insulating tape so far as a voltage difference between these coils is relatively low. However, if current and voltage values are of anxious levels for safety, the bobbin should be provided with a plurality of insulating flanges so that the respective coils may be independently wound around respective sections of the bobbin defined between each pair of adjacent flanges.
Such arrangement results in the bobbin supporting a plurality of coils which is inconveniently long for miniaturization. Furthermore, the bobbin of prior art is usually provided at opposite ends with terminal pins so that, when the needs of the coil wound around the intermediate section of the bobbin are anchored on these terminal pins, the ends of this coil must be pulled out to the associated terminal pins provided on the opposite ends of the bobbin. This often makes the coil winding operation very troublesome.